Crack detection in asphaltic mixtures by computed tomography

Computed tomography provided the basis of an advanced industrial X or g ray nondestructive testing method. The modality also provides quantitative 2-D or 3-D information which enables the detection and precise location of defects; accurate measurement of internal dimensions; and measurement and mapping of density distributions. CT technology is very versatile and is not restricted by the size, shape or composition of an object as long as adequate X or g ray transmission can be achieved. In this study, which has applied CT to the study of asphaltic mixture, it was required to detect and follow the evolution of a crack for mixture submitted to fatigue tests. The fatigue tests were done through use of diametrical compression equipment, which provided repeated loading. The trajectory of a crack is influenced by original voids in the specimen. It may be noted that voids exist at the same positions in all tomograms. With sufficient sequence of applied loadings these voids can be transformed into small crack that may increase in size, causing the collapse of the specimen. (author)